Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Lease arrangements

The following is a schedule of future minimum rental payments, exclusive of escalation clauses, on noncancelable leases and future sub-lease rental income on noncancelable leases at December 31, 2017 (in thousands of U.S. dollars):

Year	Amount
2018	$	17,195
2019	11,247
2020	9,277
2021	9,256
2022	8,895
2023-2029	38,947
Total future minimum rental payments	$	94,817
Total future sub-lease rental income through 2019	$	2,556